Radial compressors are used, for example, as turbochargers in motor vehicle engines. The construction space which is available in present-day vehicle development is severely limited due to the ever increasing number of additional assemblies and further restrictions arising from pedestrian protection or crash safety requirements. The result is that engine components, lines and air-carrying pipes compete with other components and structural parts for the respectively ideal location. In modern engine construction, the additional assemblies also include exhaust-gas turbochargers, which serve to boost the specific power output and torque in order to enhance the joy of driving and, at the same time, offer prospects for reduced emissions. Associated with turbochargers and boost concepts are other components, such as, for example, charge-air coolers, control valves and additional air pipe installations, which additionally aggravate the construction space situation.
Some typical prior art systems are discussed below:
In DE 102 50 302 A1, a swirl-generating device for the swirl-subjected flow against a compressor impeller of a compressor having a compressor housing and a charge-air suction line is disclosed. A swirl generator is provided, which can be inserted into the compressor housing and/or into the charge-air suction line and is placed in front of the compressor impeller. Viewed in cross section, the charge-air suction line is of rectilinear construction, so that the compressor is flowed against in the axial direction.
US 2003/0150212 A1 relates to an exhaust-gas turbocharger for an internal combustion engine having a turbine and compressor housing, in which there is respectively disposed a turbine and a compressor wheel, mutually connected by a shaft. The turbine housing has a spirally running inlet duct for the exhaust gases. In the inlet duct, a redoubt-like projection is provided for flow deflection purposes on the inner wall of the inlet duct so as to taper the duct cross section of the spiral inlet duct and then widen it as far as a tongue which closes off the inlet duct. The redoubt-like projection is configured as a wall reinforcement of the turbine housing.
EP 0 243 596 B1 discloses an axial swirl control for an exhaust-gas turbocharger for combustion engines with radial compressor. The radial compressor consists of an axial guide mechanism with a ring of guide blades extending radially to the charger axis and pivotable about radially aligned rotational axes, which guide blades consist essentially of circular sectors of such shape and division that, when the guide mechanism is fully closed, they almost totally cover the cross section of a flow duct and are disposed in the flow duct in a housing. The inner wall of the housing comprises, viewed in the direction of flow, a first casing of a cylindrical portion, a casing of a spherical portion, and a second cylindrical portion of lesser radius. The spherical radius of the spherical portion is equal to the radius of the first cylindrical portion. On the shafts of the unilaterally mounted guide blades, which shafts jut outward along the rotational axes, there are disposed adjusting levers, which engage in an adjusting ring concentrically enclosing the housing. The spherical portion passes in the shape of a nozzle into the second cylindrical portion. The rotational axes of the guide blades lie respectively in the blade leading edge. The transition of the housing casing from the first cylindrical portion to the spherical portion lies in the plane of the rotational axes of the guide blades.
U.S. Pat. No. 5,368,440 discloses a radial turbo engine with a rotor having a rotational axis. A diffuser has a plurality of airfoil baffle plates, which have a pressure side and a suction side. The pressure side is directed away from the rotational axis, while the suction side is orientated toward the rotational axis. At least some of the airfoil baffle plates have an angle of incidence which is substantially equal to or less than an angle of incidence corresponding to a traditional structure of pressure-sided separation flows of the airfoil baffle plates.
U.S. Pat. No. 5,730,580 discloses a turbo engine. The turbo engine comprises a set of baffle plates comprising a plurality of baffle plates arranged in a circular line, a first portion of the baffle plates being configured as “rogue” baffle plates and a second portion of the baffle plates being configured as normal baffle plates. For a given flow through the baffle plate set, the angle of incidence of the “rogue” baffle plates is different than the angle of incidence of the normal baffle plates.
The inventors herein have recognized that the construction space conditions frequently give rise to pipe installations and geometric configurations of compressor intakes which partially fail to meet the requirements of an ideal axial approach flow and circular cross sections. For instance, the pressure distribution and velocity distribution directly in front of the compressor intake and the compressor wheel differ markedly from perfectly even distributions. This can lead to irregularities in the approach flow and to local flow separations, especially at the compressor wheel, in which case the compressor output is adversely affected by the non-uniformity.
The above disadvantages can be overcome by a turbocharger system for an internal combustion engine, including: a radial compressor having a suction-side opening; and a swirl generator comprising an outlet portion facing said suction-side opening of said radial compressor, and an inlet portion angularly configured relative to said outlet portion, said swirl generator further comprising adjustable baffle plates arranged concentrically around said outlet portion.
According to the present invention, a compact configuration of the swirl generator with bends and integrated pre-swirl generation is provided, the configuration of the swirl generator giving due consideration to the limited construction space conditions within the engine compartment by taking up relatively little construction space. In addition, an enveloping compressor characteristic diagram of all swirl settings is widened, the surge limit of the compressor being shifted by the swirl to smaller mass flows. Therefore, the drivability of motor vehicles, with regard to torques in the lower region of the vehicle engine, the rated power of the engine and the acceleration characteristics, is significantly improved.
In one aspect of the present invention, the swirl generator, with its inlet portion, has a first region, which, viewed in longitudinal section, is of substantially rectangular configuration, the first region passing into a second region, which, viewed in longitudinal section, is of substantially round configuration, the outlet opening, which, viewed in longitudinal section, is of circular configuration, being made in the second region.
In another aspect of the present invention, the swirl generator, viewed in longitudinal section, is configured as a spiral housing.
In a preferred embodiment, the swirl generator has an intake cross-sectional area which corresponds to a discharge cross-sectional area. The outlet opening has an outlet diameter corresponding to an inlet diameter of the suction-side opening.
The above advantages and other advantages, and features of the present invention will be readily apparent from the following detailed description of the preferred embodiments when taken in connection with the accompanying drawings, and from the claims.